Is this tRPC converter free?

Yes. SyntaxSnap's tRPC to OpenAPI converter is completely free with no accounts, ads, or usage limits.

Does my tRPC code leave the browser?

No. All parsing and OpenAPI generation happens 100% client-side. Your proprietary router code never leaves your device.

What OpenAPI version does it generate?

The converter generates strict OpenAPI 3.1.0 JSON specifications, compatible with Swagger UI, Redoc, and other API documentation tools.

tRPC to OpenAPI Converter

Bridge the gap between internal speed and external documentation. Transform your tRPC routers into standard OpenAPI 3.1.0 specifications.

tRPC Router Input

import { z } from "zod";
import { router, publicProcedure } from "./trpc";

const isAuthed = t.middleware(({ ctx, next }) => {
  if (!ctx.user) throw new TRPCError({ code: "UNAUTHORIZED" });
  return next({ ctx: { user: ctx.user } });
});

const protectedProcedure = publicProcedure.use(isAuthed);

export const appRouter = router({
  getUser: publicProcedure
    .input(z.object({ id: z.string().uuid() }))
    .query(({ input }) => {
      return { id: input.id, name: "Alice" };
    }),

listUsers: publicProcedure
    .query(() => {
      return [{ id: "1", name: "Alice" }];
    }),

createUser: protectedProcedure
    .input(z.object({
      name: z.string().min(1).max(100),
      email: z.string().email(),
      age: z.number().int().min(18).optional(),
    }))
    .mutation(({ input }) => {
      return { id: "new-id", ...input };
    }),

deleteUser: protectedProcedure
    .input(z.object({ id: z.string() }))
    .mutation(({ input }) => {
      return { success: true };
    }),
});

OpenAPI 3.1.0 JSON

{
  "openapi": "3.1.0",
  "info": {
    "title": "tRPC Converted API",
    "version": "1.0.0",
    "description": "Auto-generated from tRPC router definition."
  },
  "servers": [
    {
      "url": "http://localhost:3000",
      "description": "Local dev server"
    }
  ],
  "tags": [
    {
      "name": "Queries",
      "description": "Read operations (HTTP GET)"
    },
    {
      "name": "Mutations",
      "description": "Write operations (HTTP POST)"
    }
  ],
  "paths": {
    "/trpc/getUser": {
      "get": {
        "summary": "Get User",
        "operationId": "getUser",
        "tags": [
          "Queries"
        ],
        "responses": {
          "200": {
            "description": "Successful response"
          },
          "400": {
            "description": "Invalid input"
          }
        },
        "parameters": [
          {
            "name": "input",
            "in": "query",
            "required": true,
            "schema": {
              "type": "object",
              "properties": {
                "id": {
                  "type": "string",
                  "format": "uuid"
                }
              },
              "required": [
                "id"
              ]
            },
            "style": "deepObject",
            "explode": true
          }
        ]
      }
    },
    "/trpc/listUsers": {
      "get": {
        "summary": "List Users",
        "operationId": "listUsers",
        "tags": [
          "Queries"
        ],
        "responses": {
          "200": {
            "description": "Successful response"
          },
          "400": {
            "description": "Invalid input"
          }
        }
      }
    },
    "/trpc/createUser": {
      "post": {
        "summary": "Create User",
        "operationId": "createUser",
        "tags": [
          "Mutations"
        ],
        "responses": {
          "200": {
            "description": "Successful response"
          },
          "400": {
            "description": "Invalid input"
          }
        },
        "requestBody": {
          "required": true,
          "content": {
            "application/json": {
              "schema": {
                "type": "object",
                "properties": {
                  "name": {
                    "type": "string",
                    "minLength": 1,
                    "maxLength": 100
                  },
                  "email": {
                    "type": "string",
                    "format": "email"
                  },
                  "age": {
                    "type": "integer",
                    "minimum": 18
                  }
                },
                "required": [
                  "name",
                  "email"
                ]
              }
            }
          }
        }
      }
    },
    "/trpc/deleteUser": {
      "post": {
        "summary": "Delete User",
        "operationId": "deleteUser",
        "tags": [
          "Mutations"
        ],
        "responses": {
          "200": {
            "description": "Successful response"
          },
          "400": {
            "description": "Invalid input"
          }
        },
        "requestBody": {
          "required": true,
          "content": {
            "application/json": {
              "schema": {
                "type": "object",
                "properties": {
                  "id": {
                    "type": "string"
                  }
                },
                "required": [
                  "id"
                ]
              }
            }
          }
        }
      }
    }
  }
}

Why convert tRPC to OpenAPI?

tRPC provides an incredible developer experience for internal monorepos, allowing you to share types between your client and server without code generation. However, when you need to expose a public API to third-party developers, they expect a standard REST interface documented with Swagger / OpenAPI.

Instead of manually maintaining a separate OpenAPI specification or rewriting your application in NestJS or Express, this tool analyzes your tRPC router definition and its underlying Zod schemas, automatically compiling them into a compliant openapi.json file ready for Swagger UI.